/*
 * Copyright (c) 2017 Baidu, Inc. All Rights Reserve.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package cn.trigram.uuid.bd.utils;

import java.lang.Thread.UncaughtExceptionHandler;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicLong;
import org.apache.commons.lang3.ClassUtils;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * 可命名的线程的线程创建工厂
 *
 * @author yutianbao
 */
public class NamingThreadFactory implements ThreadFactory {

  private static final Logger LOGGER = LoggerFactory.getLogger(NamingThreadFactory.class);

  /**
   * Thread name pre
   */
  private String name;

  /**
   * Is daemon thread
   */
  private boolean daemon;

  /**
   * UncaughtExceptionHandler
   */
  private UncaughtExceptionHandler uncaughtExceptionHandler;

  /**
   * Sequences for multi thread name prefix
   */
  private final ConcurrentHashMap<String, AtomicLong> sequences;

  /**
   * Constructors
   */
  public NamingThreadFactory() {

    this(null, false, null);
  }

  public NamingThreadFactory(String name) {

    this(name, false, null);
  }

  public NamingThreadFactory(String name, boolean daemon) {

    this(name, daemon, null);
  }

  public NamingThreadFactory(String name, boolean daemon, UncaughtExceptionHandler handler) {

    this.name = name;
    this.daemon = daemon;
    this.uncaughtExceptionHandler = handler;
    this.sequences = new ConcurrentHashMap<String, AtomicLong>();
  }

  @Override
  public Thread newThread(Runnable r) {

    Thread thread = new Thread(r);
    thread.setDaemon(this.daemon);

    // If there is no specified name for thread, it will auto detect using the invoker classname instead.
    // Notice that auto detect may cause some performance overhead
    String prefix = this.name;
    if (StringUtils.isBlank(prefix)) {
      prefix = getInvoker(2);
    }
    thread.setName(prefix + "-" + getSequence(prefix));

    // no specified uncaughtExceptionHandler, just do logging.
    if (this.uncaughtExceptionHandler != null) {
      thread.setUncaughtExceptionHandler(this.uncaughtExceptionHandler);
    } else {
      thread.setUncaughtExceptionHandler(
          (t, e) -> LOGGER
              .error("unhandled exception in thread: " + t.getId() + ":" + t.getName(), e));
    }

    return thread;
  }

  /**
   * Get the method invoker's class name
   */
  private String getInvoker(int depth) {

    Exception e = new Exception();
    StackTraceElement[] stes = e.getStackTrace();
    if (stes.length > depth) {
      return ClassUtils.getShortClassName(stes[depth].getClassName());
    }
    return getClass().getSimpleName();
  }

  /**
   * Get sequence for different naming prefix
   */
  private long getSequence(String invoker) {

    AtomicLong r = this.sequences.get(invoker);
    if (r == null) {
      r = new AtomicLong(0);
      AtomicLong previous = this.sequences.putIfAbsent(invoker, r);
      if (previous != null) {
        r = previous;
      }
    }

    return r.incrementAndGet();
  }

  /**
   * Getters & Setters
   */
  public String getName() {

    return name;
  }

  public void setName(String name) {

    this.name = name;
  }

  public boolean isDaemon() {

    return daemon;
  }

  public void setDaemon(boolean daemon) {

    this.daemon = daemon;
  }

  public UncaughtExceptionHandler getUncaughtExceptionHandler() {

    return uncaughtExceptionHandler;
  }

  public void setUncaughtExceptionHandler(UncaughtExceptionHandler handler) {

    this.uncaughtExceptionHandler = handler;
  }

}
